In recent years, the liquid crystal display (LCD) technology has developed rapidly, the screen size has become larger and the display quality has been improved. The LCD, having small volume and low power consumption and being free of radiation, plays a leading role in the field of flat panel display. The touch screen is an important component for integrating the input and output functions, and therefore has become a necessary part of portable electronic devices.
In terms of the technical principle, the touch screen may be classified into pressure-sensing touch screen, resistive touch screen, capacitive touch screen, surface acoustic wave touch screen and touch screen based on optical detection.
The touch screen based on optical detection includes multiple optical sensors capable of detecting ambient light. When a user touches a certain touch region by a finger, a quantity of the ambient light detected by an optical sensor corresponding to the touch region may be changed due to shielding of the finger. A processor may determine a position of a touch operation based on the changed quantity of the ambient light detected by the optical sensor and output information about the position of the touch operation.
In the related technology, the optical detection of the touch screen may be inaccurate. When the ambient light is of low intensity, the optical sensor can detect a very small quantity of ambient light even when the touch screen is not touched by the finger. When the user touches the touch screen by the finger, because the intensity of the ambient light is low, the quantity of the light detected by the optical sensor may not be changed obviously relative to that before the user touches the touch screen by the finger even if all the ambient light is shielded by the finger. As a result, even if the user performs a touch operation, the device is unable to detect the touch operation. When the luminance of the ambient light is changed frequently, two successive detection results of the optical sensor may differ from each other a lot even though the user does not perform any touch operation, and then the device may determine mistakenly that the user performs a touch operation.